1. Field of the Invention
The present invention relates to a conveyor device, in particular for an automatic packaging machine, provided with an automatic system for automatically changing the size of packs of products to be conveyed.
2. Description of Related Art
The invention was developed with particular regard to the application to packaging machines for paper rolls. In this sector there is a need to provide the machine with an automatic adjustment system which allows to change the format of the packs of products to be packaged without the manual intervention of operators.
Automatic packaging machines for paper rolls are often provided with a conveyor device comprising a horizontal plane of advance whereon the packs of products to be packaged are made to advance. Said conveyor device comprises a chain conveyor bearing a plurality of transverse bars and a plurality of thruster elements which extend in a transverse direction relative to said bars.
One of the adjustments necessary to adapt the packaging machine to a new format of packs consists of varying the position of the thruster elements in the transverse direction.
A known solution to effect this type of adjustment automatically is described in the document EP 1 312 549. In the solution described in this document, the conveyor device comprises a plurality of chains, each of which bears a respective series of thruster elements. The adjustment of the distance in transverse direction between the thruster elements is obtained by varying the relative distance between the chains.
The displacement of the chains in the transverse direction entails the need substantially to modify the entire structure of the conveyor with respect to a traditional machine lacking the automatic size change device.